As ultrawide bandwidth (UWB) technology becomes increasingly desirable for wireless devices, it becomes more and more necessary to set a standard for UWB operations. The Institute for Electrical and Electronic Engineers (IEEE) has designated that the 802.15.3™ standard be drafted to cover high rate wireless personal area networks (WPANs), which covers UWB communications.
One proposal offered for the 802.15.3™ standard is a direct sequence-ultrawide bandwidth (DS-UWB) proposal. In general, a UWB physical (PHY) layer protocol uses high rate, ultra-wide bandwidth pulses to send data at rates up to 1000 Mbps. One particular DS-UWB approach divides the available spectrum into upper and lower bands, the lower band being between 3.1 to 5.15 GHz and the upper band being between 5.825 and 10.6 GHz. Information is then encoded in these bands using direct-sequence spread spectrum techniques. In particular, pulse filtering/shaping may be used with BPSK/QPSK modulation with 50% excess bandwidth, root-raised-cosine impulse response. The chip rate, center frequency, and symbol rate in this DS-UWB proposal can be harmonically related.
It is desirable for any UWB technology to capable of supporting multiple application types. Two key applications are wireless in-room video distribution and handheld applications. However, each of these two applications has significantly different device requirements. The class of in-room video distribution applications is characterized by a need for high data rates with multiple users, robust performance, and low sensitivity to power requirements. In contrast, the class of handheld applications imposes stringent requirements for low cost and power consumption, with the additional requirement for scalability to extremely high data rates (1000+ Mbps).
Therefore, it is desirable that any DS-UWB PHY layer proposal enable a UWB device using the IEEE 802.15.3a standard to provide both the high performance capabilities required by wireless in-room video distribution, as well as the low power/cost scalability required for high-rate handheld applications.